Healing time of experimentally induced distal limb wounds in horses is not reduced by local injection of equine-origin liquid amnion allograft.

Objective: To assess the efficacy of an equine-origin liquid amnion allograft (ELAA) derived from both amniotic fluid and amniotic membrane on the healing time of experimentally induced distal limb wounds in horses.

Animals: 8 adult horses.

Procedures: On day 0, horses were anesthetized and a 2.5 X 2.5-cm, full-thickness skin wound was created on the dorsal aspect of each metacarpus and bandaged. On day 9, wound margins were injected with ELAA (treatment) or 0.9% NaCl (control). Bandages were changed at specific intervals through day 91 and, on each occasion, wounds were photographed to allow calculation of wound area. Exuberant granulation tissue was resected, if present. Wounds were deemed healed when completely epithelialized. Mean wound area was compared between groups throughout the study period.

Results: Only 1 wound (control) remained unhealed at day 91. No difference was found between the treatment and control groups in either wound area over time (P = 1.0) or time for wounds to reduce in size by 95% (P = .2) Exuberant granulation tissue required resection twice (1 control wound and 1 treatment wound).

Clinical Relevance: In this model, a single treatment with ELAA administered locally by SC injection did not accelerate distal limb wound healing in horses. However, it is possible that naturally occurring, chronic, or nonhealing wounds would respond differently.